1. Field of the Invention
The present invention relates to a thin film magnetic head and a method of manufacturing the same, and more particularly to a composite type thin film magnetic head constructed by stacking an inducting type writing magnetic transducing element and a magnetoresistive type reading magnetic transducing element, particularly a technique for improving a performance of a thin film writing magnetic head.
2. Description of the Related Art
Recently a surface recording density of a hard disc device has been improved, and it has been required to develop a thin film magnetic head having an improved performance accordingly.
The composite type thin film magnetic head has a structure for stacking a recording head intended for the writing and a reproducing head intended for the reading out, and a magnetoresistive element has been widely used in order to improve the performance of the reproducing head.
In general, as such a magnetoresistive element, the element utilizing anisotropic magnetoresistive (AMR) effect has been used so far, but there has been further developed a GMR reproducing element utilizing a giant magnetoresistive (GMR) effect having a resistance change ratio higher than the normal anisotropic magnetoresistive effect by several times. In the present specification, elements exhibiting a magnetoresistive effect such as these AMR and GMR reproducing elements are termed as a magnetoresistive reproducing element or MR reproducing element.
By using the AMR reproducing element, a very high surface recording density of several gigabits per a unit square inch has been realized, and a surface recording density can be further increased by using the GMR element. By increasing a surface recording density in this manner, it is possible to realize a hard disc device which has a very large storage capacity of more than 10 gigabytes and is still small in size. A height (MR Height: MRH) of a magnetoresistive reproducing element is one of factors which determine a performance of a reproducing head including a magnetoresistive reproducing element. The MR height MRH is a distance measured from an air bearing surface on which one end face of the magnetoresistive reproducing element is exposed to the other edge of the element remote from the air bearing surface. During a manufacturing process of the magnetic head, a desired MR height MRH can be obtained by controlling an amount of polishing the air bearing surface.
At the same time, a performance of a recording head is also required to be improved, in accordance with improvement of performance of the reproducing head. In order to increase a surface recording density, it is en necessary to make a track density on a magnetic record medium as high as possible. For this purpose, a width of a write gap at the air bearing surface has to be reduced to a value within a range from several micron meters to several sub-micron meters. In order to satisfy such a requirement, the semiconductor manufacturing process has been adopted for manufacturing the thin film magnetic head.
One of factors determining a performance of an inductive type thin film writing magnetic head is a throat height TH. This throat height TH is a distance of a pole portion measured from the air bearing surface to an edge of an insulating layer which serves to separate a thin film coil from the air bearing surface. It has been required to shorten this distance as small as possible. The reduction of this throat height is also decided by the amount of grinding from the air bearing surface. Therefore, in order to improve the performance of the thin film magnetic recording head, it is important that the recording head and the reproducing head are formed with best balance.
FIGS. 1a, 1b-9a, and 9b are cross-sectional views vertical to the air bearing surface showing the successive manufacturing steps of a conventional standard thin film magnetic head, and a cross sectional view in which the magnetic pole section is cut in parallel to the air bearing surface. Moreover FIGS. 10-12 are a cross-sectional view of the entire conventional completed thin film magnetic head a cross-sectional view of the magnetic pole section, and a plan view of the entire thin film magnetic head, respectively. Moreover, the thin film magnetic head of this embodiment is a composite type thin film magnetic head formed by stacking the induction type thin film writing magnetic head and the MR reproduction reading element.
First of all, as shown in FIGS. 1a and 1b, an Insulation layer 2 consisting of for example alumina (Al2O3) is deposited on a basic substrate consisting of non-magnetic and electrical insulation material for example, such as AlTiC with a thickness of about 5-10 xcexcm.
Next, as shown in FIGS. 2a and 2b, a lower shield layer 3 which composes a magnetic shield protecting the MR reproduction element of the reproducing head from the influence of the external magnetic field, is formed with the thickness of 3 xcexcm.
Afterwards, as shown in FIGS. 3a and 3b after spattering and depositing alumina as a shield gap layer 4 of a thickness of 100-150 nm, a magnetic resistance layer 5 consisting of a material with the effect of magnetic resistance and composing the MR reproduction element is formed on the shield gap layer with a thickness of tens nano meter, thereby making high precise mask alignment.
Then as shown in the FIG. 4, again, a shield gap layer 6 is formed so that the magnetic resistance layer 5 is embedded in the shield gap layers 4 and 6.
Next, as shown in the FIG. 5, a magnetic layer 7 consisting of permalloy is formed with the film thickness of 3 xcexcm. This magnetic layer 7 has not only a function of the upper shield layer which magnetically shields the MR reproduction element together with the above described lower shield layer 3, but also has a function of a lower magnetic layer of the thin film magnetic writing head. Herein, for convenience sake of the explanation, this magnetic layer 7 is called as a first magnetic layer by paying attention to it a magnetic layer composing a writing magnetic head.
Then, on the first magnetic layer 7, after a light gap layer 8 consisting of non-magnetic material, for example alumina is formed with film thickness of about 200 nm, a second magnetic layer 9 consisting of material with high saturation magnetic flux density such as, for example, permalloy (Ni: 50 wt %, Fe: 50 wt %) and nitride iron (FeN) is formed with a desired shape by high precise mask alignment.
Second ma molded in a given shape is called a pole chip, and the width of the track is defined as a width W.
In this case, when a dummy pattern 9xe2x80x2 for connecting a lower pole (first magnetic layer) and an upper pole (third magnetic layer), which is formed latter, are formed simultaneously, it is possible to make an opening for through-hole after a polishing or chemistry-mechanical (CMP).
In order to prevent a width of effective writing track from being widened, that is, in order to prevent a magnetic flux from being widened in the lower pole at the data writing, also a gap layer 8 in surroundings of the pole chip 9 and the lower pole 7 (first magnetic layer) are etched by an ion beam etching, such as, ion miring. Even though its state is shown in FIG. 5b, this structure is called as a trim, and this portion becomes a magnetic pole section in the first magnetic layer.
Next, as shown in FIGS. 6a and 6b, after an insulating layer, for example, alumina film 10 is formed with the thickness of about 3 xcexcm, the whole is, for example, made smooth by CMP.
Subsequently, after forming a photoresist layer 11 of electrical insulation to a given pattern by the mask alignment of high precision, a thin film coil 12 as the first layer consisting, for example, of copper is formed on the photoresist layer 11.
Continuously, as shown in FIGS. 7a and 7b, after forming an insulating photoresist layer 13 is formed on the thin film coil 12 by the mask alignment of high accuracy again, in order to make the surface smooth, the calcining (baking) processing is given with the temperature of for example 250-300xc2x0 C.
In addition, as shown in FIGS. 8a and 8b, the thin film coils 14 as the second layer are formed on the smoothed surface of this photoresist layer 13. Next, after forming a photoresist layer 15 with highly accurate mask alignment on the thin film coils 14 as this second layer, in order to make the surface smooth again, the calcining (baking) processing is given with the temperature of for example 250xc2x0 C.
As described above, the reason why photoresist layers 11, 13 and 15 are formed with m alignment of high accuracy, is that throat height and MR height are defined by a reference position at the end edge of the magnetic pole section side of the photoresist layer.
Next, as shown in FIGS. 9a and 9b, a third magnetic layer 16 consisting of for example permalloy is selectively formed on the second magnetic layer 9 (pole chip) and the photoresist layers 11, 13 and 15 with the thickness of 3 xcexcm according to desired pattern.
This third magnetic layer 16 comes in contact with the first magnetic layer 7 at a rear position away from the magnetic pole section through a dummy pattern 9xe2x80x2, thin film coil 12, 14 is extended through a closed magnetic circuit composed by the 1st, 2nd and 3rd magnetic layers.
In addition, an overcoat layer 17 consisting of alumina deposited from the exposed surface of the third magnetic layer 16.
Finally, the side surface forming the magnetic resistance layer 5 and the gap layer 8 is ground, thereby forming an air bearing surface (ABS) 18 opposite to the magnetic record medium, Magnetic resistance layer 5 is also ground in the formation process of this air bearing surface 18, and thus, MR reproduction element 19 is obtained. In this way, the above described throat height TH and the MR height MRH are decided. Its appearance is shown in FIG. 10. In an actual thin film magnetic head, the conductor and the point of contact pad for performing electrical connection for the thin film coils 12, 14 and a MR reproduction element 19 are formed, but this is not shown.
As shown in FIG. 10, an angle xcex8 between line segments S connecting corners of side surfaces of photoresist layers 11,13,15 for isolating the thin film coils 12,14 and an upper surface of the third magnetic layers 16 is called as an apex angle thereby becoming an important factor for deciding a performance of the thin film magnetic head together with the above described throat height TH and MR height.
Moreover, as shown in FIG. 12 by the plane, a width W of the magnetic pole section 20 between the second magnetic layer 9 and the 3rd magnetic layer 16 is made narrow, and the width of the track recorded in the magnetic record medium is defined by this width, so that it is necessary to narrow this width W as much as possible to achieve a high surface recording density. Moreover, in this FIG. 12, for the shake""s of convenience of drawing, the thin film coils 12, 14 are made concentric circle.
Well, in forming conventional thin film magnetic head, especially, the problem is that after forming the coil, the coil section covered with the photoresist insulation layer and risen in the mountain shape, especially, it is a difficulty of a fine formation of the upper pole (yoke pole) formed along the inclined part (Apex). That is, the hitherto, in case of forming the upper pole, after plating the material for the upper pole such as permalloy on the mountain shaped coil with the height of about 7-10 xcexcm, the photoresist is spread with the thickness of 3-4 xcexcm, after which a given pattern is formed by using the photolithography technology. Herein, If 3 xcexcm or more is necessary as the film thickness of resist that the patterning is performed by the register strike on the mountain shaped coil, the photoresist of the about 8-10 xcexcm thickness will be spread under the inclined portion.
One the one hand, in the upper pole formed on the write gap layer which is formed on the surface and the smooth surface of a certain mountain shaped coil section having de height difference of about such 10 xcexcm, it is necessary to form the narrow track of the recording head near the edge in the photoresist insulation layer (11, 13 of for example FIG. 7). Therefore, it is necessary to form the pattern of the width of 1 xcexcm with the photoresist film of thickness of 8-10 xcexcm.
However, even if the narrow width pattern of 1 xcexcm level is formed with a photoresist film as thick as 8-10 xcexcm, in case of exposing the photolithography, the pattern crumble or the like due to the reflection of light is generated, and the decrease in the resolution is forced due to the thick resist, so that it is extremely difficult to form a top pole for forming the narrow track by the patterning with accuracy.
Then, as is shown in the above conventional embodiment, assuming that data is written with the pole chip capable of forming the narrow track width of the recording head, after forming this pole chip, by adopting a method of connecting the upper pole to this pole chip, in other words, by adopting a structure divided into two, that is, a pole chip for determining the track width and an upper pole for inducing magnetic flux, the above problem has been advantageously improved.
However, in the thin film magnetic head formed as in the above, particularly, in the recording head, the problem described as follows was left now as in the past.
(1) The contact area of a pole chip and an upper pole is small, moreover, the contact portion touches it vertically, so that it is easy to saturate magnetic flux with the part, therefore, the writing characteristic of satisfying enough is not obtained.
(2) Throat height TH and MR height MRH are decided based on the edge on the pole portion side of the insulating layer which insulating separates the thin film coil, but the insulating layer is weak to heat since it is usually formed with a photoresist organic insulating layer. Therefore, it melts by heating about 250xc2x0 C. added when the thin film coil is formed or softens, and the pattern size of the insulating layer changes, and the size of throat height TH and MR height MRH might shift from the design value of the desire.
(3) The positional relation of a poles and an upper pole is decided by alignment at photolithography, so that as seen from the air bearing surface, this positional relation is shifted to one side greatly, but in case, at a writing is performed even in the upper pole and thus the effective track width is widened. Therefore, the malfunction of writing the data in the place other than in the hard disk board to be recorded originally, is generated.
An object of the present invention is to achieve the above problems with effectively and to provide a thin film magnetic head in which the contact area of a pole chip and an upper pole is effectively expanded, and the saturation of the magnetic flux at the magnetic pole section worried at the hitherto is completely canceled, and its effective manufacturing method.
Also, another object of the present invention is to a thin film magnetic head in which the pattern of the insulation layer as a standard at the position to the air bearing surface does not melt by heat-treating about 250xc2x0 C. added at the time of forming the thin film coil, and thus, the throat height TH and MR height can be obtained as the desired design value with stability, and its effective manufacturing method.
Moreover, other object of the present invention is to provide a thin film magnetic head in which widening of the width of the effective track and the decrease in the yield or the like were also canceled, and its manufacturing method.
According to the present invention, there is provided a thin film magnetic head comprising: a first magnetic layer having a pole portion opposite to a magnetic record medium, a second magnetic layer opposite to the magnetic record medium and having a pole portion with a width defining a width of a record track, for constructing an air bearing surface together with an end face of the pole portion and an end face of the pole portion of the first magnetic layer, a third magnetic layer contacted to the second magnetic layer at the side opposite to the first magnetic layer and magnetically coupled to the first magnetic layer at a rear position separated form the air bearing surface, a gap layer consisting of non-magnetic material inserted between the pole portion of the first magnetic layer and the pole portion of the second magnetic layer, a thin film coil having a portion supported between the first magnetic layer and the second and third magnetic layers the ate isolated by an insulating layer, and a base substrate for supporting the first, second and third magnetic layers, the gap layer, the insulating layer and the thin film coil, characterized in that the second magnetic layer is extended to the region after than the pole portion of the first magnetic layer along a part of the face at the side opposite to the first magnetic layer, of the insulating layer supported in the state isolating the thin film coil, thereby touching the second magnetic layer to the third magnetic layer at the extended region.
In a suitable embodiment of the thin film magnetic head according to the present invention, the width of second magnetic layer is widened at the region rear the pole portion.
In this case, the widened angle of the second magnetic layer at the region rear than the pole portion is 40xcx9c180xc2x0.
In addition, in the present invention, the second magnetic layer consists of substance having a high saturation flux density.
Also, the tip portion of the second magnetic layer is made backed up from the air bearing surface, so as not expose the touched portion of the third magnetic layer and the second magnetic layer on the air bearing surface. The distance backed up from the air bearing surface is made substantially 2-5 xcexcm.
In addition, in the embodiment of the thin film magnetic head according to the present invention, the insulation layer where the end edge of the magnetic pole section side becomes a reference position to the air bearing surface is provided on the above first magnetic layer, the surface of this insulation layer is covered with the gap layer consisting of the above nonmagnetic material, and the above second magnetic layer is arranged along the surface opposite to the above insulation layer of this gap layer the above second magnetic layer.
Moreover, in the present invention, a magnetoresistive reading reproducing element insulated in electrically and shielded in magnetically is arranged so as to expose its end face on the above air bearing surface between the above basic substance and the first magnetic layer to construct a composite thin film magnetic head.
In addition, the manufacturing method of the thin film magnetic head according to the present invention comprising: step of forming a first magnetic layer having a magnetic pole section so as to support it by a basic substrate, a step of forming a first insulating layer having an end edge of the magnetic pole section side as a reference position for the air bearing surface, a step of forming a gap layer consisting of non-magnetic material on the magnetic pole portion in the above first magnetic layer and the above first insulation layer, a step of forming a second magnetic layer over the magnetic pole portion in the above first magnetic layer and the rear region therefrom on the gap layer, a step of forming a thin film coil supported in the state isolated with each other by the second insulation layer above the first insulating layer, a step of forming on the above second insulation layer a third magnetic layer coming in contact with the above second magnetic layer at the region rear rather than at least the magnetic pole portion, and coming in contact with the above first magnetic layer at a rear position away from the above air bearing surface, and a step of forming an air bearing surface opposed to the magnetic record medium by grinding the above basic substance, the magnetic pole portion of the first and second magnetic layers and the gap layer placed therebetween.
In a suitable embodiment of the manufacturing method of the thin film magnetic head according to the present invention, the above second magnetic layer is formed in such a manner that the width of a magnetic layer in a rear region is gradually expanded than the magnetic pole portion.
Moreover, in a suitable embodiment of the manufacturing method of the thin film magnetic head according to the present invention, before forming the gap layer where the above first magnetic layer consists at least of non-magnetic material on the magnetic pole portion, the insulation layer where the edge on the magnetic pole portion side becomes a reference position to the air bearing surface, is formed, and in case of forming the gap layer, the above insulation layer is covered with non-magnetic thin film which forms the gap layer.
Moreover, in the manufacturing method of the thin film magnetic head according to the present invention, a magnetoresistive reading reproducing element insulated in electrically and shielded in magnetically is arranged between the above basic substrate and the first magnetic layer to construct a composite thin film magnetic head.
In case of manufacturing such a composite type thin film magnetic head, the first shield layer for performing a magnetic shielding on the above basic substrate, the magnetic resistance material film is formed thereon while being embed in a fourth insulation layer, after which the above first magnetic layer also serving as the second shield layer is formed, and in the grinding step for forming the above air bearing surface, the above first shield layer is ground and the above magnetic resistance material film is ground, thereby forming a magnetoresistive reproducing element which exposes its end surface on the air bearing surface.